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futex: Convert to compiler context analysis

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Convert the sparse annotations over to the new compiler context
analysis stuff.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260121111213.950376128@infradead.org
This commit is contained in:
Peter Zijlstra
2026-01-14 12:08:28 +01:00
parent 68bcd8b6e0
commit 16df04446e
5 changed files with 35 additions and 6 deletions
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2
kernel/futex/Makefile
View File

@@ -1,3 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
CONTEXT_ANALYSIS := y
obj-y += core.o syscalls.o pi.o requeue.o waitwake.o

9
kernel/futex/core.c
View File

@@ -864,7 +864,6 @@ void __futex_unqueue(struct futex_q *q)
/* The key must be already stored in q->key. */
void futex_q_lock(struct futex_q *q, struct futex_hash_bucket *hb)
__acquires(&hb->lock)
{
/*
* Increment the counter before taking the lock so that
@@ -879,10 +878,10 @@ void futex_q_lock(struct futex_q *q, struct futex_hash_bucket *hb)
q->lock_ptr = &hb->lock;
spin_lock(&hb->lock);
__acquire(q->lock_ptr);
}
void futex_q_unlock(struct futex_hash_bucket *hb)
__releases(&hb->lock)
{
futex_hb_waiters_dec(hb);
spin_unlock(&hb->lock);
@@ -1443,12 +1442,15 @@ static void futex_cleanup(struct task_struct *tsk)
void futex_exit_recursive(struct task_struct *tsk)
{
/* If the state is FUTEX_STATE_EXITING then futex_exit_mutex is held */
if (tsk->futex_state == FUTEX_STATE_EXITING)
if (tsk->futex_state == FUTEX_STATE_EXITING) {
__assume_ctx_lock(&tsk->futex_exit_mutex);
mutex_unlock(&tsk->futex_exit_mutex);
}
tsk->futex_state = FUTEX_STATE_DEAD;
}
static void futex_cleanup_begin(struct task_struct *tsk)
__acquires(&tsk->futex_exit_mutex)
{
/*
* Prevent various race issues against a concurrent incoming waiter
@@ -1475,6 +1477,7 @@ static void futex_cleanup_begin(struct task_struct *tsk)
}
static void futex_cleanup_end(struct task_struct *tsk, int state)
__releases(&tsk->futex_exit_mutex)
{
/*
* Lockless store. The only side effect is that an observer might

17
kernel/futex/futex.h
View File

@@ -217,7 +217,7 @@ enum futex_access {
extern int get_futex_key(u32 __user *uaddr, unsigned int flags, union futex_key *key,
enum futex_access rw);
extern void futex_q_lockptr_lock(struct futex_q *q);
extern void futex_q_lockptr_lock(struct futex_q *q) __acquires(q->lock_ptr);
extern struct hrtimer_sleeper *
futex_setup_timer(ktime_t *time, struct hrtimer_sleeper *timeout,
int flags, u64 range_ns);
@@ -311,9 +311,11 @@ extern int futex_unqueue(struct futex_q *q);
static inline void futex_queue(struct futex_q *q, struct futex_hash_bucket *hb,
struct task_struct *task)
__releases(&hb->lock)
__releases(q->lock_ptr)
{
__futex_queue(q, hb, task);
spin_unlock(&hb->lock);
__release(q->lock_ptr);
}
extern void futex_unqueue_pi(struct futex_q *q);
@@ -358,9 +360,12 @@ static inline int futex_hb_waiters_pending(struct futex_hash_bucket *hb)
#endif
}
extern void futex_q_lock(struct futex_q *q, struct futex_hash_bucket *hb);
extern void futex_q_unlock(struct futex_hash_bucket *hb);
extern void futex_q_lock(struct futex_q *q, struct futex_hash_bucket *hb)
__acquires(&hb->lock)
__acquires(q->lock_ptr);
extern void futex_q_unlock(struct futex_hash_bucket *hb)
__releases(&hb->lock);
extern int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb,
union futex_key *key,
@@ -379,6 +384,9 @@ extern int fixup_pi_owner(u32 __user *uaddr, struct futex_q *q, int locked);
*/
static inline void
double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2)
__acquires(&hb1->lock)
__acquires(&hb2->lock)
__no_context_analysis
{
if (hb1 > hb2)
swap(hb1, hb2);
@@ -390,6 +398,9 @@ double_lock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2)
static inline void
double_unlock_hb(struct futex_hash_bucket *hb1, struct futex_hash_bucket *hb2)
__releases(&hb1->lock)
__releases(&hb2->lock)
__no_context_analysis
{
spin_unlock(&hb1->lock);
if (hb1 != hb2)

9
kernel/futex/pi.c
View File

@@ -389,6 +389,7 @@ static void __attach_to_pi_owner(struct task_struct *p, union futex_key *key,
* Initialize the pi_mutex in locked state and make @p
* the owner of it:
*/
__assume_ctx_lock(&pi_state->pi_mutex.wait_lock);
rt_mutex_init_proxy_locked(&pi_state->pi_mutex, p);
/* Store the key for possible exit cleanups: */
@@ -614,6 +615,8 @@ int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb,
static int wake_futex_pi(u32 __user *uaddr, u32 uval,
struct futex_pi_state *pi_state,
struct rt_mutex_waiter *top_waiter)
__must_hold(&pi_state->pi_mutex.wait_lock)
__releases(&pi_state->pi_mutex.wait_lock)
{
struct task_struct *new_owner;
bool postunlock = false;
@@ -670,6 +673,8 @@ out_unlock:
static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
struct task_struct *argowner)
__must_hold(&q->pi_state->pi_mutex.wait_lock)
__must_hold(q->lock_ptr)
{
struct futex_pi_state *pi_state = q->pi_state;
struct task_struct *oldowner, *newowner;
@@ -966,6 +971,7 @@ retry_private:
* - EAGAIN: The user space value changed.
*/
futex_q_unlock(hb);
__release(q.lock_ptr);
/*
* Handle the case where the owner is in the middle of
* exiting. Wait for the exit to complete otherwise
@@ -1090,6 +1096,7 @@ no_block:
if (res)
ret = (res < 0) ? res : 0;
__release(&hb->lock);
futex_unqueue_pi(&q);
spin_unlock(q.lock_ptr);
if (q.drop_hb_ref) {
@@ -1101,10 +1108,12 @@ no_block:
out_unlock_put_key:
futex_q_unlock(hb);
__release(q.lock_ptr);
goto out;
uaddr_faulted:
futex_q_unlock(hb);
__release(q.lock_ptr);
ret = fault_in_user_writeable(uaddr);
if (ret)

4
kernel/futex/waitwake.c
View File

@@ -462,6 +462,7 @@ retry:
}
futex_q_unlock(hb);
__release(q->lock_ptr);
}
__set_current_state(TASK_RUNNING);
@@ -628,6 +629,7 @@ retry_private:
if (ret) {
futex_q_unlock(hb);
__release(q->lock_ptr);
ret = get_user(uval, uaddr);
if (ret)
@@ -641,11 +643,13 @@ retry_private:
if (uval != val) {
futex_q_unlock(hb);
__release(q->lock_ptr);
return -EWOULDBLOCK;
}
if (key2 && futex_match(&q->key, key2)) {
futex_q_unlock(hb);
__release(q->lock_ptr);
return -EINVAL;
}